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rkelsen 04-17-2021 07:51 AM

Query about smart TV on local network
 
So I have a Linux machine on the local network at home, which also has a so-called smart TV attached. On the Linux machine, I use a small program called gkrellm to visually monitor various things.

I noticed that even with no other programs open there are continuous small amounts of traffic coming to the Linux machine.

Running a tcpdump tells me that it is continuously receiving packets from the TV. It's not much, in terms of traffic. Perhaps 120 bytes per second, but it sometimes jumps to 600 bytes per second. A drop in the bucket, but it annoys me. How do I stop it? The TV needs to be able to see this computer, so firewalls are out of the question. It even happens when the TV is in 'stand by' mode.

Emerson 04-17-2021 08:09 AM

There are stories about smart appliances, not only TVs, how they collect data and "call home". I saw an article about smartTV which scanned the whole LAN for media files and sent the list to manufacturer, someone like you got suspicious and used wireshark on it. The feature was ON by default. When turned OFF it still scanned and sent the list, but also added insult to injury and mentioned the feature is disabled by user. The best practice is to make sure your Smart Things have internet access blocked in the router, IMHO.
It depends how sensitive you are about your privacy. For me even using Windows 10 is out of question because of their privacy policy (not the only reason, though). Leave alone Alexa and other such systems, they give me creeps. But people are using them.

enorbet 04-17-2021 12:37 PM

The easiest and most thorough fix is to setup your router/firewall (or add one if yours doesn't have a feature to ask permission for outgoing packets) since smart TVs are the least of your security concerns. They are only interested in your media preferences, but CPUs have access to everything on your PC, hard drives, ethernet, and wifi, even when shutdown but PSU remains On (soft off). For example Intel CPUs have MCE which is built into BIOS/UEFI and is protected proprietary code fully capable of accessing and sending who knows what and on unsecured networking.

teckk 04-17-2021 02:43 PM

Quote:

I noticed that even with no other programs open there are continuous small amounts of traffic coming to the Linux machine.
Analyze those packets to see what they are. They could be IP6 neighbor discovery, multicast packets like 224.0.0.1, 224.0.0.1: igmp, or the TV trying to be the master browser on the network, or a continuous ARP who has what address on the network. Microsoft is famous for all of that, and it won't quit. Also it could be doing a heartbeat pulse every second, trying to bridge itself.

You'll have to discover what that TV is doing.

Give that TV a fixed IP address if it will take it, then block it to the outside world at your firewall until you figure out what it is doing.

Quote:

It even happens when the TV is in 'stand by' mode.
Thank you for the info. I don't have a smart TV in the house on purpose.

Emerson 04-17-2021 02:54 PM

Quote:

I don't have a smart TV in the house on purpose
I have two, not used as smartTV, both are "buffered" with Kodi boxes, not only I control what goes in and what goes out Kodi is also much more user friendly.

rkelsen 04-18-2021 09:46 PM

Quote:

Originally Posted by teckk (Post 6242195)
Analyze those packets to see what they are.

I'm not smart enough for that. So I sent the output from tcpdump to someone who is.

He told me it's all multi-cast DLNA traffic, and (thankfully!) that the computer isn't responding to it.

So the TV is just creating noise on the network looking for DLNA devices. Which is probably why a remote control appears on my phone when the kids are watching videos on a certain website.
Quote:

Originally Posted by teckk (Post 6242195)
Thank you for the info. I don't have a smart TV in the house on purpose.

Yeah, I'm going to try disabling DLNA to see if it has an impact on the way we use the TV.

Emerson 04-18-2021 10:56 PM

This is what it is doing with your computer, you still don't know if it is communicating with remote sites on the internet.

rkelsen 04-18-2021 11:17 PM

Quote:

Originally Posted by Emerson (Post 6242582)
This is what it is doing with your computer, you still don't know if it is communicating with remote sites on the internet.

I've firewalled all traffic from it to the outside world.


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